In the field of a clinical test, there has been an advancement of automation in the pursuit of an improved measurement precision and also laborsaving. More specifically, clinical testing devices such as a dispensation device for dispensing a certain amount of liquid, a dilution device for diluting a test specimen to a certain ratio, and further, an automatic analyzer in which a process from quantifying the test specimen and dispensing a reagent to a measurement step is fully automated, have been so far developed.
In the foregoing clinical testing devices, a supply tube, such as a pliable tube, is connected to an opening portion of the vessel in which the reagent for analysis is contained, and the reagent sucked from the vessel is supplied to a predetermined spot through the supply tube.
Meanwhile, a suction tube to be inserted into the reagent for analysis is provided in the vessel, the reagent in the vessel is sucked through the suction tube and supplied to the clinical testing device through the supply tube.
As the suction tube, a pliable tube, a hard pipe or a suction tube whose edge is connectively provided with a member having a certain weight and a suction hole for preventing the suction tube from floating onto a liquid surface in the reagent vessel is used.
However, in using the pliable suction pipe or hard suction pipe, or suction tube whose edge is connectively provided with the member having the certain weight and the suction hole, in the case in which the reagent is sucked when a remaining volume of the reagent in the vessel is lessened, air as well as the reagent is inconveniently sucked into the tube, which generated air bubbles in the sucked reagent.
Of the generated air bubbles, those having a large size disappear within a relatively short length of time, while it takes a considerable amount of time before the small and fine air bubbles disappear. Further, when the air bubbles are once generated in the reagent including a surface active agent, it becomes even more difficult for the air bubbles to disappear.
In the foregoing situation, there was a resultant problem that the generated air bubbles were counted as particles in measuring the number of the particles in the measured test specimen by means of a particle counting device, for example, which made it not possible to obtain an accurate number of the particles included in the measured test specimen.
Further, in a device which is designed to obtain a concentration of a measurement object included in the test specimen through the measurement of an absorbance, the small and fine bubbles change the absorbance, which generated another problem that it was not possible to obtain the accurate concentration.
In order to solve the foregoing problems, a liquid suction device (see No. H09-297146 of the Publication of the Unexamined Japanese Patent Applications) comprising a suction pipe dipped in liquid contained in a liquid vessel and a float valve provided in the vicinity of an edge of the suction pipe for gradually closing an opening at the edge of the suction pipe in response to the lowering of a liquid level in the liquid vessel has been proposed.
However, in the recited liquid suction device, the edge of the suction pipe is gradually closed in response to the liquid level, which generates a risk of the air incorporation immediately before the halt of the liquid suction. Therefore, the foregoing method may not be suitably applied to certain types of analyzers and testing devices.